Question

Potential energy of a 2 kg body at some point on a planet is $-16\times {10}^4\text{Joules}$. Find the escape speed of the body at same point.

• A. 11.2 km/s
• B. 0.4 km/s
• C. 5.6 km/s
• D. 1.4 km/s

Answer 1

The correct option is B 0.4 km/s

For escape $T.E.=K.E+P.E\ge 0$

$\frac{1}{2}m{v}^2-16\times {10}^4\ge 0$

$v^2\ge 16\times {10}^4$

$v\ge 400\text{m/s}$

$v_{\text{min}}=400$ $m/s$